The present invention is directed generally to tape measures and, more particularly, a locking mechanism for controlling the extraction and retraction of a tape from a tape measure housing.
Modern tape measures generally include a coiled tape that is spring biased towards a retracted position. A protective housing surrounds the tape and spring and includes an aperture through which a distal end of the tape extends. The distal end of the tape is pulled away from the housing during use, and when released, the spring pulls the tape back into the housing so that the tape assumes the retracted position.
Various types of locking mechanisms are utilized for maintaining the tape in any given extended position. Locking mechanisms usually bind the tape within the housing and are actuated by the user through a slide or push button positioned on an outer edge of the housing. Thus, the tape may be extracted to the desired length and a locking mechanism engaged to hold the tape at that distance. The locking mechanism may then be disengaged and the tape is retracted into the housing.
Many previous tape measures only provide for the locking mechanism to be either completely engaged or completely disengaged. These devices do not provide for any intermediate levels of control which may be advantageous in various environments. The lack of any intermediate level limits the functionality and environments in which the tape measure may be used. To overcome this problem, some tape measures are equipped with two separate locking mechanisms. One locking mechanism provides for a positive lock function, essentially mimicking the engaged and disengaged functionality of the previous models. The second locking mechanism provides a drag function which opposes the retraction or extraction of the tape relative to the housing, but typically at a lower grip force level than the xe2x80x9cfullxe2x80x9d locking condition. However, each of the two locking mechanisms require separate elements which must be positioned within the housing. See for example U.S. Pat. No. 5,007,178. A two activator arrangement thus complicates the tape measure design, usually leading to a higher overall cost. Additionally, the housing must be larger to contain the tape and at least two separate locking mechanisms which is undesirable as hand tools must easily fit within the user""s hands, attach to work belts, or be stored within limited spaces such as a crowded tool box. Other tape measures may have either, but not both types of braking mechanisms.
Therefore, there is a need for a tape measure having a single locking mechanism operable in three modes: a free mode characterized by a disengaged or open position in which the tape is free to retract or extend from the housing; a lock mode characterized by a lock position in which the tape is prevented from moving relative to the housing; and a maintain mode characterized by a maintain position in which the tape is prevented from retracting, but is allowed to extend relatively freely.
The present invention is directed to a tape measure having a variety of locking positions for controlling the retraction and extraction of a tape. The variety of positions allows a user to more easily handle and manipulate the tape to his or her advantage, especially when they are doing multiple tasks.
The tape measure includes a flexible tape subject to a bias towards a retracted position and a housing substantially surrounding the tape when it is in the retracted position. A locking lever is connected to the housing and includes a tip for selectively engaging the tape. The locking lever is positionable between at least three positions corresponding to the three functional modes. A free mode positions the locking lever and tip away from the tape for relatively free retraction and extraction of the tape from the housing. A lock mode engages the tip against the tape requiring increased force to extract or retract the tape relative to the housing. A maintain mode engages the tip against the tape to require force to retract the tape into the housing, but require little additional force with respect to the free mode for extraction.
Preferably, the locking lever pivots about an axis to accommodate the three modes. The locking lever includes a lock arm that extends to the tape, and a grip arm that extends outside the housing allowing for the user to control the modes. A tip is connected to the end of the lock arm for contacting the tape. The tip is constructed of a pliable material. In one embodiment, the tip is positioned off-center from the centerline of the lock arm in the lock mode for increased holding.